The present invention relates to the field of waste disposal. More particularly, the invention relates to methods for safely treating and disposing of infectious biomedical waste and other hazardous materials.
Today hospitals and other health-care organizations produce considerable amounts of infectious waste. This type of waste includes surgical gowns, surgical gloves, needles, instruments, glass, culture dishes, and other disposable matter exposed to blood and other body fluids of patients. Such waste is classified as xe2x80x9cregulated medical wastexe2x80x9d under federal regulations, disposal of which must comply with strict governmental regulations. As used herein, the term xe2x80x9cregulated medical wastexe2x80x9d refers to infectious waste, to waste containing infectious agents, as defined below, and to any waste that poses a threat of transmission of infection to humans or animals, i.e. potentially containing infectious agents capable of causing infection in humans or animals. Such regulated medical waste may include, but is not limited to, tissue, cloth, plastic, paper, animal carcasses, bedding and other matter potentially containing infectious agents.
Recently, Health-care organizations as well as Regulatory Agencies have been concerned with the adequacy of existing cleaning and disposal methods. It has been discovered that some potentially harmful cells, such as prokaryotes, or harmful proteins may survive standard autoclaving procedures. Thus, more effective sterilization techniques have been sought for treating solid infectious biomedical waste, i.e., regulated medical waste.
In addition, universities and other research facilities likewise produce a significant level of such waste. In conducting experiments in cell lines, tissues or upon animals, it is common to introduce dyes, toxic chemicals or infectious agents into the test subject. After completion of the test and analysis, due to the introduction of infectious agents or hazardous materials, the remaining tissue or animal carcass falls under the classification of regulated medical waste. In addition, animal waste, animal bedding, handling materials and other matter exposed to animal body fluids or excretions may also need to be treated as infectious or hazardous waste, thus requiring disposal in accordance with applicable governmental regulations.
In addition, it is common for health care organizations today to clean materials, instruments or surface areas exposed to infectious agents, including zoonotic agents, with disinfectants such as formaldehyde or glutaraldehyde. Spent cleaning solution is considered hazardous liquid waste and must be disposed of in compliance with government regulations. The cost of disposing of such waste, on an institutional basis, can be quite costly. In addition, formaldehyde, glutaraldehyde, phenols and like materials are commonly used for embalming tissues and in fixation of infectious biological materials. Thus, these tissues and the fixative agents must likewise be disposed of in compliance with government regulations.
Currently, the two methods commonly used in disposing of hazardous waste and regulated medical waste are incineration and burial. Presently Federal law imposes strict regulations for incineration of hazardous waste and infectious biomedical waste. However, incineration may be further limited by state and local agencies. For example, incineration of regulated medical waste or other hazardous waste is not available at all in some jurisdictions such as the major metropolitan areas of New York City, San Francisco and Chicago. Furthermore, the general process of incineration itself, even when no hazardous materials or regulated medical wastes are involved, is subject to additional regulations, such as those requiring a direct license from a state or local environmental agency. Additionally, future increases in the requirements for incinerator designs and function under clean air regulations put in doubt the continued availability of incineration as a method of disposing such wastes.
Presently, the only real alternative to incineration is autoclaving the solid waste and then burying the waste material in a licensed waste disposal facility. Currently there are a limited number of such sites in the United States. It is extremely costly to dispose of infectious medical waste by this method. Further, one will appreciate that the cost is exceedingly high for waste that comprises matter which, but for the potential infectious agents, could be disposed of using less costly local disposal facilities. Due to the extremely high cost associated with land burial and the limitations on access to licensed land burial sites, the feasibility of land burial as a method of disposing of such waste remains an ever growing concern for research and health-care facilities.
The known methods of disposing of regulated medical wastes generated by many universities, health-care and research facilities faces an uncertain future under the ever narrowing scope of environmental laws. Furthermore each is extremely costly, putting an unneeded drain on the already strained resources of universities, health-care organizations and research facilities. Thus, a need exists for methods for disposing of infectious bio-medical wastes and other hazardous materials which is safe, environmentally friendly and less expensive than existing disposal means.
The aforsaid needs are satisfied and the limitations of the prior art overcome, in accordance with the principles of the present invention, by providing a method for producing safely disposable compositions from regulated medical waste. This method for treating regulated medical waste comprises the steps of providing a highly basic solvent, immersing the regulated medical waste within the highly basic solvent, and heating. The regulated medical waste contains infectious agents, which comprise hydrolyzable material (i.e. biological tissues, cells, or cell components containing proteins or lipids capable of undergoing hydrolysis or saponification in the highly basic solvent). Furthermore, the infectious agents are capable of causing infection in humans or animals and are selected from the group consisting of bacteria, organisms, and proteinaceous material.
To assure degradation of all infectious wastes, including prokaryotes, the heating step comprises heating the highly basic solvent and immersed regulated medical waste to a temperature greater than 130xc2x0 C. and under an absolute pressure greater than 2.79 atmospheres (gauge pressure  greater than 1.79 atm) and for a time sufficient to digest the hydrolyzable material. A sterile solution comprising non-toxic biodegradable materials and containing sterile solid waste free of infectious agents is produced. Degradation of the regulated medical waste preferably involves treating the waste at a temperature around 135xc2x0 C. and under an absolute pressure about 3.1 atmospheres (gauge pressure about 2.1 atm), and more preferably, around 150xc2x0 C. to 155xc2x0 C. and about 5 atmospheres (gauge pressure about 4 atmospheres). At a temperature around 180xc2x0 C., the corresponding pressure will be about 10 atmospheres (gauge pressure about 9 atm). Generally, it is preferable not to exceed temperatures of about 180xc2x0 C. Unless indicated otherwise, pressures herein are absolute in atmospheric units, and the corrresponding gauge pressure reading may be calculated by subtracting 1 atmosphere from the absolute pressure.
The tissue or other matter potentially containing the infectious medical waste is allowed to remain within the highly basic solvent until the hydrolyzable matter is fully digested, thereby forming a sterile solution and sterile solid waste. The aqueous solution and any solid waste may then be disposed of through standard means, such as a sanitary sewage system and local landfill facilities. However, it will be appreciated that the amount of solid waste to be disposed of is substantially reduced by the present invention.
In another aspect, hazardous materials may be removed from the digest and separately disposed of in an appropriate manner, such as in a landfill designated for such hazardous wastes or in a specially licensed high temperature furnace. Paraffin or wax may be added to the regulated medical waste prior to or after digestion. Upon heating of the materials, the paraffin or wax melts and becomes distributed throughout the aqueous solution. After the waste has been fully digested and the aqueous solution is allowed to cool, the lipid-like materials separate out from and float to the surface of the aqueous phase where they resolidify upon cooling to room temperature. Lipid soluble waste materials may then be removed from the aqueous phase upon separation of the lipid phase because they have become incorporated within the lipid phase. Thus, removing the lipid phase from the solution effectively also removes lipid soluble hazardous materials not degraded or otherwise consumed in the alkaline treatment.
Accordingly, it is a principle object of this invention to provide a method for safely disposing of tissue and other matter containing infectious biological waste (i.e., regulated medical waste) and/or other hazardous materials. One advantage of this invention is that it allows for safe disposal of the regulated medical waste at significantly less expense to the research or health-care facility without harming or increasing the risk of harm to the environment. An additional advantage of this invention is that the method may be utilized without geographic limitations, satisfying existing governmental regulations at the federal, state and local level. Another advantage of this invention is that it preserves the ever shrinking area available in the land burial sites.